Ion implantation systems are mechanisms utilized to dope semiconductor substrates with impurities in integrated circuit manufacturing. In such systems, a dopant material is ionized and an ion beam is generated there-from. The ion beam is directed at the surface of a semiconductor wafer or workpiece to implant ions into the wafer. The ions of the beam penetrate the surface of the wafer and form regions of desired conductivity therein, such as in transistor fabrication, for example. A typical ion implanter includes an ion source for generating the ion beam, a beamline assembly including a mass analysis apparatus for directing and/or filtering (e.g., mass resolving) ions within the beam, and a target chamber containing one or more wafers or workpieces to be treated.
Batch type of implanters include a spinning disk support for moving multiple semiconductor wafers through the ion beam. The ion beam impacts the wafer surface as the support rotates the wafers through the ion beam. Serial implanters treat one wafer at a time. The wafers are supported in a cassette and are withdrawn one at time and placed on a support. The wafer is then oriented in an implantation orientation so that the ion beam strikes the single wafer. These serial implanters use beam shaping that can deflect the beam from its initial trajectory and often are used in conjunction with coordinated wafer support movements to selectively dope or treat the entire wafer surface.
Ion implanters are advantageous because they allow for precision with regard to both quantity and placement of dopants within workpieces. In particular, ion implanters allow the dose and energy of implanted ions to be varied for given applications. The ion dose controls the concentration of implanted ions, where high current implanters are typically used for high dose implants, while medium current implanters are used for lower dose applications. Ion energy is used to control junction depth in semiconductor devices, for example, where the energy determines the depth to which ions are implanted within a workpiece.
It can be appreciated that given the trend in the electronics industry to scale down electronic devices to produce smaller, yet more powerful devices (e.g., cell phones, digital cameras, etc.), that the semiconductors and integrated circuits (e.g., transistors, etc.) utilized in these devices are continually being reduced in size. The ability to “pack” more of these devices onto a single semiconductor substrate, or portion thereof (known as a die) also improves fabrication efficiency and yield. It can be appreciated that controlling ion implantations plays an important role in successfully increasing packing densities. For example, control over the implantation energy of low energy, high current beams may allow implants to be performed to shallower depths to produce thinner devices and enhance packing densities. Additionally, there may be smaller margins for error with regard to the orientation (e.g., angle) of the ion beam relative to the mechanical surface and/or crystalline lattice structure of the workpiece. Accordingly, mechanisms and techniques that facilitate more control over ion implantations are desirable.